Ghost Racer at San Marino
Beat something like 1 min 23 second at San Marino and a ghost racer, an old-style Mclaren, will begin to race along side you.

Gold Racer
Go into Exhibition mode and select Driver Williams. Using your Control Stick, edit his last name to "Pyrite." Exit all the way to the Start screen, then re-enter. A new Gold Driver will be available in Exhibition, Time Trial and 2 Player mode.

Hawaiin Bonus Track
Go into Exhibition mode and select Driver Williams. Using your Control Stick, edit his last name to "Vacation." Exit all the way
to the Start screen, then re-enter. You'll find a bonus track after the European Grand Prix.

Silver Racer
Go into Exhibition mode and select Driver Williams. Using your Control Stick, edit his last name to "Chrome." Exit all the way to the Start screen, then re-enter. A new Silver Driver will be available in Exhibition, Time Trial and 2 Player modes.

Unlimited Acceleration
Go to gold or silver racer and select rookie and manual. Stay in first gear and you will have a never ending acceleration.

Unlimited Fuel
When you are in Grand Prix mode go to the paddock screen. Put your fuel down as far as it will go. Then when you race you will have unlimited fuel for the next race.
NOTE: This only works in Grand Prix mode.